Free shipping, discounts and other promotions are driving the increase, said Mike Berry, director of industry research at MasterCard Advisors. “That is a continuation of the trend we saw for the Monday after Thanksgiving. That day, online sales were up 18.3% over the same Monday after Black Friday in 2009,” he said. Berry added that online sales were up 17.2% for the full week after Black Friday.

Many online holiday promotions started the second week of November, making for a longer online shopping season this year, noted McNamara. The continuing shift of retail market share from bricks-and-mortar stores to e-tailers “has really driven some of the growth rates this year,” he said.

Consumer spending through December 11 is growing at a faster rate than the modest year-over-year increase seen during the back-to-school shopping season, according to MasterCard. Some segments, such as electronics and appliances, are flat due to falling prices for big-screen TVs and other big-ticket items, but others, such as e-commerce, are up significantly.

Several key sectors are up sharply, signaling consumers are more willing to spend money on non-essential items than they were last year. Apparel sales are up 9.8% over last year, jewelry is up 2.6%, and luxury items excluding jewelry increased 2.6%.

The increases in the jewelry and luxury categories could mask a hidden demand, said McNamara. He explained that jewelry and luxury items sell better at the end of the season, and last-minute sales are the bulk of holiday spending in both segments. For example, he noted about 30% of jewelry sales occur in the 10 days before Christmas.